It's exactly as is says, it turns on the main beams when it can't "see" a car in front or one coming the other way.

More specifically, it does so at night (minimal ambient lighting available). A nice feature if you drive on country roads at night (going to work or going home). The few times its activated for me its been spot on. I suspect it'll get more usage in the winter though...

you know how many times i've broken a nail that way?
i know its not the most useful option
but i just thought about this yesterday
and it struck me as the kind of option that could potentially be coded

you know how many times i've broken a nail that way?
i know its not the most useful option
but i just thought about this yesterday
and it struck me as the kind of option that could potentially be coded